In wireless communication systems, an IQ imbalance effect caused by imbalance in terms of phase and gain between an in-phase path (I path) and a quadrature path (Q path) of a receiving end is a common issue when radio frequency (RF) signals are received. The IQ imbalance effect results in image aliasing in an orthogonal frequency division multiplexing (OFDM) communication system, which may directly influence the received signal. In particular, when the receiving end is an apparatus with lower cost, such as a sensor node in machine-to-machine (M2M) communication, the influence becomes more significant.
Several solutions, as described below, are known to solve the IQ imbalance effect. One of the solutions is to insert a longer preamble or a pilot signal so that the characteristic of the IQ paths can be obtained by the receiver by using the longer preamble or the pilot signal. Such solution has a lower complexity, but however, different processes are required in correspondence to different standards, and the transmission rate of data is also influenced. Another solution is to perform blind estimation using a time domain signal that is received. Although such solution is applicable to all of the conventional standards, it takes longer time for convergence and requires a higher computational complexity. Still another is backtracking IQ path estimation, wherein an error factor is used to correct the compensation based on each outcome of compensation. However, such solution also takes a longer time for convergence. In the solutions above, issues of a lower data transmission rate or an overly high complexity usually come along with solving the imbalance effect. Thus, eliminating image aliasing to the received signal while paying attention to the hardware cost of a system as well as the computation complexity has become an important issue in the field.